1. Field of the Invention
The present invention relates to a sine wave light-adjusting apparatus. In particular, the present invention adjusts the switching period of a switch and utilizes a flywheel effect to achieve the light-adjusting effect.
2. Description of the Related Art
Generally, the light-adjusting apparatus of lamps is controlled by a Thyristor phase control method. It utilizes the excellent characteristics of the Thyristor to change the conduction angle by the phase control method for controlling the brightness of the lamps. Because the Thyristor is a semi-permanent element, the failure rate is low and can be used for a long time. It is extensively used for the lamps.
Reference is made in FIG. 1, which shows a circuit of a light-adjusting apparatus with a Phase Modulation method of the prior art. A light-adjusting circuit 1 composed of the Thyristor (Silicon Controlled Rectifier—SCR/Triode AC semiconductor switch—TRIAC) controls the conduction angle of the output voltage Vout on the two ends of the loading 2. FIG. 2 shows the waveform of the output voltage Vout of the prior art. In FIG. 2, the circuit of the light-adjusting apparatus can adjust and control the conduction angle of the output voltage Vout to achieve the light-adjusting effect.
However, the light-adjusting apparatus with a Phase Modulation method of the prior art controls the discontinuous and deformed output voltage Vout to provide the power for the loading. By this way, the power factor (PF) of the loading is reduced. Therefore, the inputted alternating current AC110V cannot be utilized efficiently and the energy is wasted. Furthermore, light-adjusting apparatus with a Phase Modulation method generates noise due to the control circuit output non-sine waves.